1. Field of the Invention
The present invention relates to an apparatus for cleaning a wire of a wire saw useful for slicing ingots or the like to thin wafers.
2. Brief Description of the Prior Art
After top and tail parts are cut off an ingot produced by a pulling method or the like, the ingot is ground at its periphery, subjected to orientation flat processing and then sliced to wafers of predetermined thickness. Although an inner blade slicer has been used so far for slicing the ingot, it does not well cope with a tendency of enlargement of wafers in diameter. Therefore, a wire saw machine using a piano wire has been recently adopted in response to enlargement of wafers.
A conventional wire saw has three grooved rollers 1-3, one of which (the roller 3) is coupled to a drive motor 4, as shown in FIG. 1. A wire 5 is pulled out from a reel 6, passed around the grooved rollers 1 to 3 multiple times and then wound on another reel 7. A tensioner 8 applies a tension to the wire 8. Thus, the wire 5 travels in a stretched state along a travel path around the grooved rollers 1 to 3.
An ingot 9 to be sliced is fixed to a holder 10 using a proper adhesion jig and located at a position between the grooved rollers 1 and 2. The ingot 9 is sliced to a plurality of wafers by cutting motion of the wire 5. During slicing, slurry 11 is supplied from a slurry tank 11 through a supply tube 13 to a nozzle 14, sprayed onto the wire 5, collected in a pan 15 and then returned to the slurry tank 12, in order to promote the cutting motion. The slurry 11 is cooled by circulation between the slurry tank 12 and a heat exchanger 16.
The slurry 11 still adheres onto the wire 5 due to its stickiness, even when the wire 5 after being used for slicing the ingot 9 travels toward the reel 6 or 7. If the wire 5 together with the slurry 11 is wound as such on the reel 6 or 7, the slurry 11 scatters in the circumference during winding and causes contamination of a wiring chamber wherein the reels 6, 7 are located.
There are various members and tools except the reels 6, 7 in the wiring chamber. For instance, a dancer roller 17 and a traverser 18 for adjusting a winding number of the wire 5 on the reels 6, 7 and for controlling a tension applied to the wire 5. Scattering and accumulation of the slurry 11 in such wiring chamber likely induces occurrence of mechanical troubles. In this sense, the wiring chamber shall be kept in a dean state free from scattering and accumulation of the slurry 11. Unfavorable introduction of the slurry of 11 into the wiring chamber also accelerates abrasion of various rollers located in the wiring chamber.
The slurry 11 can be washed off from the wire 5 by a washer provided at a travelling path of the wire 5 between the slicing chamber and the wiring chamber so as to spray a cleaning liquid to the wire 5. However, such a washer shall have enough length along the travel path of the wire 5, in order to sufficiently wash off the slurry 11 by spraying the cleaning liquid to the running wire 5. As a result, a huge washer is necessitated. In addition, removal of the slurry 11 is insufficient only by spraying the cleaning liquid, so that some residual slurry is involved together with the wire 5 in the reels 6, 7.